A guide wire is used to guide a catheter to treat or diagnose vascular stenosis in a cardiac artery or in a peripheral artery such as a limb or the like. The guide wire used for such procedure is inserted to the vicinity of a vascular stenosis site or a target site together with a catheter with the distal end of the guide wire allowed to project from the distal end of the catheter. In this state, the catheter is shifted along the guide wire to guide the distal end portion of the catheter to the vicinity of the vascular stenosis site.
The blood vessel requiring the above-mentioned procedure has an indurate stenosis site, a partially steeply bending flexion or the like. Therefore, the guide wire may be sometimes hard to pass through. Because of this, the guide wire used to guide the catheter into the blood vessel requires not only adequate flexibility and restoring performance for bending, but also pushability and torque transmissibility for transmitting the operation of the proximal end portion to the distal end side, and further anti-kink performance (anti-bending performance) and the like. (The pushability and torque transmissibility are generically referred to as “operability”.)
To improve the operability (pushability) of the guide wire, the guide wire has been covered on an outer surface with a material adapted to make satisfactory the sliding performance with the catheter inner surface. An example is the guide wire described in Japanese Patent Laid-Open No. Hei 5-168717, referred to as Patent Document 1 hereinafter. The guide wire described in Patent Document 1 is such that a distal portion is coated with a hydrophilic resin and a proximal portion which is to be handled is covered with a fluorinated resin different from that for its distal end side portion in order to improve a grip force (gripping force) encountered when the guide wire is gripped at its hand portion. However, even if the portion to be handled is covered with the fluorinated resin, since the fluorinated resin surface has a relatively low friction coefficient relative to a finger, the grip force is not increased. That is to say, there arises a problem in that since the portion to be handled is slippery, a pushing and turning force is hard to transmit depending upon a to-be-inserted site or a catheter so that operability is not high.
There is a guide wire that is covered with a hydrophilic resin, wherein the distal end side portion of its covering layer is removed and a spiral slip-prevention member is provided at such a removed portion. An example is disclosed in Japanese Patent Laid-Open No. Hei 7-328126, referred to as Patent Document 2 hereinafter. However, although the guide wire described in Patent Document 2 exhibits a grip force when operated by gripping the portion provided with the slip-prevention member, if such a portion is inserted into the lumen of the catheter, just then the slip-prevention member functions to lower sliding performance. If the slip-prevention member is provided only at the proximal end of the guide wire, the intermediate portion of the guide wire, i.e., a portion not provided with the slip-prevention member will be gripped during insertion. Therefore, the hydrophilic resin (the covering layer) functions to lower the grip force, so that unnecessary time will be spent for the insertion.
There is also a guide wire in which a wire is spirally wound to form concavity and convexity on a jacket surface (a covering layer) made of PTFE or the like and thereafter the convexity is subjected to hydrophilic or hydrophobic coating. An example is disclosed in International Application Publication No. WO 05/44358 referred to as Patent Document 3 hereinafter. Although the guide wire described in Patent Document 3 improves sliding performance, since the material with a low friction coefficient such as PTFE or the like is used as the material forming the jacket, an improvement in grip force cannot be expected. Further, the step for forming concavity and convexity is complicated and it is difficult to form uniform concavity and convexity.